1. Field of the Invention
The present invention relates to a solar cell and a method of manufacturing the same, and more particularly to a bifacial solar cell and a method of manufacturing the same.
2. Description of the Related Art
Recently, interest in alternative energy sources that can replace existing energy sources such as petroleum or coals has increased due to depletion of existing energy sources. Among these alternative energy sources, solar cells are receiving attention because solar energy is abundant and solar cells do not cause problems in terms of environmental pollution. Solar cells are classified into solar thermal cells to generate steam needed for rotation of a turbine using solar heat and photovoltaic solar cells that use semiconductors to convert photons into electrical energy. Photovoltaic solar cells are generally referred to as “solar cells” (hereinafter referred to as “solar cells”).
Solar cells are semiconductor elements that convert sunlight into electrical energy and have a p-n junction structure, and basic structures thereof are the same as those of diodes.
When light is incident on a solar cell, the solar cell absorbs the incident light and thus interaction between the incident light and a material constituting a semiconductor of the solar cell occurs. As a result, electrons and holes, which are minority carriers, are formed, and the electrons and holes move towards corresponding electrodes connected to each other to obtain electromotive force. This process is referred to as the photovoltaic effect.
Meanwhile, bifacial solar cells produce electricity such that sunlight is absorbed by both front and rear surfaces of the solar cell. While a general solar cell produces electricity as a front surface thereof absorbs sunlight, a bifacial solar cell absorbs sunlight from both front and rear surfaces thereof and thus current formed is higher than a general solar cell, which results in production of a greater amount of electricity.
When a conventional bifacial solar cell includes a p-type substrate, an n-layer is formed on a front surface of the p-type substrate and a p-layer is formed on a rear surface thereof.
However, when a bifacial solar cell is formed using such conventional manufacturing method, energy conversion efficiencies at front and rear surfaces thereof differ, and the energy conversion efficiency of the rear surface thereof is generally lower (i.e., approximately 2%) than that of the front surface of the solar cell.